PRESS RELEASE
Knowing what phase is
Leoni determines electrical lengths of cables in its own lab
Friesoythe, 1 December 2015 – The signal quality at the end of a
transmission path is defined, among other factors, by the electrical
parameters of a cable. In most cases the time offset due to a
transmission path is not relevant and is therefore given generous
tolerance, but when it is a matter of simultaneous signal transfer across
various parallel cables, the ‘electrical length’ of an assembled cable is
more important in certain applications than its mechanical length. In its
laboratory, Leoni cuts its cables phase-matched to the customer’s
request and takes this electrical length into account during assembly.
The demand is normally for phase-matched lengths on cables two to
three metres long, but, depending on the frequency, the mechanical
length of cable is not limited.
In a vacuum, signal waves spread at the speed of light (approx. 300,000 km/s).
In the case of a cable, the signal spreads between the conductor(s) and the
braid, i.e. normally inside the insulation. The relative dielectric constant of this
insulation determines the signal speed. Minimal, production-related differences
in the dielectric constant across various conductors are normally permitted
within the framework of defined tolerances. The mechanical length of
assembled cables usually has priority.
But what is to be done when virtually no tolerances in the signal transfer across
various assembled cables are allowed; as in the case, for example, of MRT
coiled wiring or highly sensitive measurement cable systems? In such
applications, propagation delay differences between several cables would have
an immediate, negative effect on image quality or measurement readings.
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PRESS RELEASE
Accuracy is wanted
As a cables specialist, Leoni has an extensive range of electrical and
mechanical testing methods. In its own laboratory, skilled members of staff can
determine the electrical length of an assembled cable. The underlying
parameters are calculated depending on the cable’s structure and prescribed
frequency as part of the cable’s development and recorded in the design data.
These parameters are measured with the help of vector network analysers and
the mechanical length is adjusted to the electrical length.
In one example, all cables are cut ‘too long’, assembled unilaterally and
trimmed precisely down to a few degrees by means of measuring the reflected
phase. Accuracy is also called for when it comes to the final fitting of the
second connector. The length of insulation to be stripped for this purpose is
taken into account in calculating the parameters in the design data and the
prescribed measurements are adhered to exactly by Leoni staff when
assembling the cable.
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 Related illustration material can be downloaded next to this release at
https://www.leoni-healthcare.com/en/news/details/knowing-what-phase-is/
About the Leoni Group
Leoni is a global supplier of wires, optical fibers, cables and cable systems as well as
related services for the automotive sector and further industries. Leoni develops and
produces technically sophisticated products from single-core automotive cables
through to complete wiring systems. Leoni’s product range also comprises wires and
strands, standardised cables, special cables and cable system assemblies for various
industrial markets. The group of companies, which is listed on the German MDAX,
employs about 75,000 people in 31 countries and generated consolidated sales of
EUR 4.1 billion in 2014.
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PRESS RELEASE
Contact person for trade press
Contact person for economic press
Birte Wendeln
Marketing Business Unit Healthcare
LEONI Special Cables GmbH
Phone +49 (0)4491-291-173
Fax
+49 (0)4491-291-5173
E-Mail birte.wendeln@leoni.com
Sven Schmidt
Corporate Public & Media Relations
LEONI AG
Phone +49 (0)911-2023-467
Fax
+49 (0)911-2023-231
E-Mail presse@leoni.com
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